The invention concerns a method and apparatus for manufacturing a cushioning and insulating material and more specifically concerns a cushioning material formed of layers, preferably of plastic material having sealed areas defining closed air cells or pockets.
Cushioning and insulating material formed of layers of plastic material joined together to form closed pockets have heretofore been manufactured with rather large, complex and expensive machines. It was necessary to provide means for applying suction to form the areas in the sheet material while heat was applied to seal the layers together and separate machines were required to form the cushioning material in different widths. For these reasons a large capital outlay was required and thus such machines were available only in plants where the plastic sheet material was made. The present invention makes it practical to make insulating and cushioning material of any desired width locally at the point of use rather than in the plant where the sheet material is manufactured from raw chemical ingredients.
According to the invention, apparatus of simplified construction is provided in which two layers of sheet material in web, or ribbon, form, preferably a thermoplastic film, are moved intermittently along a fabricating line pathway through a tube forming station to corrugate one of the webs into tubular formations, through a longitudinal sealing station, to seal the webs together along longitudinal seam lines, and then the longitudinally seamed material is fed through a transverse sealing station to form transverse seams while air is blown into the longitudinally formed tubes, creating closed, sealed, air-filled, expanded cells out of the longitudinal tube formations. The sealing stations may have heating elements for heat sealing thermoplastic, preferably polyethylene, or thermally sealable layers formed out of the ribbons of plastic film. As used in this specification and in the claims below the terms web, ribbon and film are interchangeable.
Accordingly, it is a principal object of this invention to provide a new and improved method and apparatus for the manufacture of cushioning materials as outlined above.